The present invention relates to an angular rate sensor and, more particularly, is suitably applied to an angular rate sensor having a function of detecting displacement of a structure present on the inside of a sensor.
The angular rate sensor is a device that converts an angular rate into an electric signal and detecting the angular rate. In recent years, the development of devices that detect various physical amounts such as pressure, acceleration, and an angular rate has been accelerated.
For example, as the angular rate sensor, sensors of an oscillation type, a rotation type, a gas type, and an optical type are developed. In particular, in recent years, for the purpose of improvement of mass productivity and a reduction in size, the development of oscillation type and rotation type angular rate sensors employing a silicon microfabrication technique is mainly carried out.
The oscillation type angular rate sensor is a device that causes an oscillator to oscillate at a predetermined resonant frequency and detects, as an electric signal, displacement of the oscillator involved in angular rate application from the outside.
In this way, most of the devices employing the silicon microfabrication technique detect displacement of a structure included in a semiconductor device for detecting physical amounts. Therefore, the devices sensitively react to stress or the like applied to the semiconductor device from the outside. In particular, deformation of the semiconductor device due to packaging stress generated when the semiconductor device is packaged causes a measurement error or the like and deteriorates reliability of a sensor device.
Therefore, the sensors employing the silicon microfabrication technique indispensably needs to have a packaging structure in which external force is not applied to physical amount detecting units or physical amount detecting devices. When such sensors are mounted on automobiles, in order to enable mounting of the sensors in a severe environment such as an engine room, it is indispensably necessary to adopt a packaging structure having high reliability.
As a packaging structure of electronic components including semiconductor devices such as the sensors, for example, structures such as an electronic component and an electronic module described in JP-A-2004-47897 and JP-A-2009-33114 are known. The electronic component described in JP-A-2004-47897 has a configuration in which a piezoelectric element and an electronic component are packaged on a metallic core board and covered with a metal cap connected by soldering to core metal of the metallic core board and sealing resin is filled on the inner side of the metal cap. The electronic module described in JP-A-2009-33114 has a configuration in which an electronic component is packaged on a multilayer board and covered with a metal shield electrically connected to a ground electrode of the multilayer board and the inner side of the metal shield is sealed by epoxy resin or the like.
However, in the configuration of the electronic component described in JP-A-2004-47897, since the sealing resin is filled on the inner side of the metal cap, the semiconductor device packaged on the board is deformed by stress application to the semiconductor device. In particular, when the semiconductor device employing the silicon microfabrication technique is packaged, it is difficult to secure reliability because, for example, a measurement error occurs. In the configuration of the electronic module described in JP-A-2009-33114, since the electronic component is packaged on the multilayer board, electromagnetic noise tends to be applied to the packaged electronic component. In particular, when the semiconductor device is packaged, it is difficult to secure reliability because, for example, measurement is unstable.